Creating a unique digital fingerprint using existing combinational logic

Creating digital circuits of ever decreasing size leads to certain imperfections that cannot be avoided. Although these imperfections are not significant enough to hinder the digital circuit operation, they are random and can be exploited to create a unique digital fingerprint which can be used as a chip identity. Unique digital fingerprints can be created on any number of circuits and in our research we created 60 digital fingerprints, all of which were uniquely identifiable. The digital fingerprint is a function of the amount of combinational logic that forms the circuit and can be applied to any sufficiently large combinational circuit. In this research, we have used a combinational multiplier and we show how a longer combinational path leads to a larger number of captured glitches. In addition, we show the effects of temperature changes on the digital fingerprint.